A simple review of many NFL “expert” preseason predictions shows how few believed the Philadelphia Eagles could win the NFC East, let alone take the conference title with home-field advantage throughout the NFC playoffs. And that was before the injuries began happening with almost comical regularity.

Those who decided Dallas or the New York Giants – teams that combined for fewer regular-season wins (12) than the Eagles had on their own (13) – would win the division are now red-faced as Philadelphia prepares to face New England in Super Bowl LII. Just how were the Eagles able to overcome injuries both early and late to win the NFC?

The answer requires a complicated explanation, one that we’ll dissect on both sides of the ball in a two-part series ahead of the Super Bowl. But what’s important to remember throughout is that STATS foretold Philadelphia’s success prior to the 2017 season even beginning, backing it with X-Info data and advanced analytics.

STATS’ propriety model calculated the Eagles having the second-ranked overall roster in the NFL heading into the season when taking into account depth and performance – both past and projected – at each position. That may have seemed like a stretch considering the Eagles were coming off their second straight 7-9 campaign with a second-year quarterback who had an overall underwhelming debut season.

The X-Info roster rankings factor in much more than just the first unit, though. It helps provide context to a team’s depth and balance – almost an outline for the next-man-up mentality should someone fall to injury or simply underperform. We’ll get to the Eagles’ defense and the issues it faced in Part II next week, but first let’s get into how they found success offensively.

STATS Research notes Philadelphia is the first team since the 2003 Patriots to reach the Super Bowl without having an 800-yard rusher and a 900-yard receiver. Prior to that New England squad, the last team to do so was the 1990 New York Giants. The Eagles had the seventh-ranked offense this season, up from 22nd in coach Doug Pederson’s first season, when they also went with an offensive balance that spread to many different options.

The difference became the quality of talent, as Philadelphia traded receiver Jordan Matthews to Buffalo and signed Alshon Jeffery and Torrey Smith. It also signed running back LeGarrette Blount from New England and cut Ryan Mathews. Of course, there’s no metric in the world able to predict Carson Wentz would go from throwing 16 touchdowns and 14 interceptions as a rookie to a 33-to-7 ratio while becoming an MVP candidate the very next year, but a reasonable leap was expected.

STATS X-Info ranked Philadelphia with the second-best roster before it acquired former 1,200-yard rusher Jay Ajayi from Miami for a fourth-round pick Oct. 31, but the addition of undrafted free agent Corey Clement was underrated in the wake of Darren Sproles’ left ACL tear and broken right forearm suffered on the same play Sept. 24. Almost a month later to the day, nine-time Pro Bowl left tackle Jason Peters tore his right ACL and MCL, forcing unproven Halapoulivaati Vaitai to step into the starting lineup.

We noted shortly before the season opener that Wentz should have much better weapons than he did in 2016 with the additions of Jeffery and Smith, and for the most part that became true. Wentz’s completion percentage to strictly wide receivers rose from an NFL-worst 44.9 to 56.8 this season as his receivers created more separation with 6.9 yards at catch (fifth) after ranking 28th with a 5.04 average last year.

Wentz also become more efficient. His third-down passer rating went from 67.0 (on 156 attempts) in 2016 to 123.7 (on 124 attempts) this year, sparking an overall improvement from 79.3 to 101.9. Despite playing three fewer games, Wentz still saw an increase of pass plays of 20-plus yards (39 to 40).

It might seem odd that STATS X-Info calculated the Eagles having the 29th-ranked receiving corps, even with Nelson Agholor having more catches this season (62) than in his first two NFL campaigns combined (59). But that’s only because of the position distinction going essentially three deep, when in reality Wentz found his options all over the field. Pass-catching depth is the best way to describe it.

Zach Ertz finished with team highs of 74 catches and 824 yards along with eight touchdowns. Fellow tight ends Trey Burton and Brent Celek combined for 36 more catches, with Burton adding five touchdowns and Celek catching another. The Eagles targeted tight ends 31.5 percent of the time, which was 9.5 percent above league average and the second-highest mark in the league behind Indianapolis.

Also, six running backs caught at least five passes, and four had at least 47 carries as the Eagles tied for fourth in the NFL in yards per rush at 4.47. So while Philadelphia’s positional roster ranking for wide receivers from X-Info isn’t flattering, running backs ranked 12th and tight ends sixth. The production was spread between a plethora of players at each of those spots and, combined with Wentz’s improvement, more than justify the original overall roster ranking.

And we haven’t even discussed the injury that was supposed to derail Philadelphia’s Super Bowl hopes. Wentz’s torn ACL in Week 14 forced into action Nick Foles, a former Eagles Pro Bowler cast off from St. Louis and Kansas City the previous two seasons. Few people believed Foles could step in and replace Wentz’s production. Just as few people likely realized that Pederson worked with Foles previously as the Eagles’ quarterbacks coach in each of their first stints with the franchise.

Foles and Joe Montana are the only players in NFL history to complete at least 75 percent of their passes in back-to-back playoff games after Foles threw for 352 yards and three touchdowns in a 38-7 win over Minnesota in the NFC championship game. Foles picked up where Wentz left off, with 14 different players catching a pass in Foles three regular-season starts and two postseason games. Five different running backs carried the ball in that span and Philadelphia has continued winning with the same offensive game plan.

When one cog goes down, the Eagles plug in another and the machine keeps churning smoothly. It’s a trend that’s continued throughout the season and into the Super Bowl, not simply because of depth, but the quality of that depth.